Oscillating winding weight for a timepiece with an automatic movement and timepiece fitted with such a winding weight

ABSTRACT

The invention concerns an oscillating winding weight for a timepiece including a heavy portion secured to a connecting element connecting said heavy portion to an arbour fixed to the movement, said weight being intended to be rotatably mounted on said arbour, characterised in that said connecting element is made of a transparent or translucent material.

BACKGROUND OF THE INVENTION

The present invention concerns an oscillating winding weight for atimepiece with an automatic movement. More particularly, the inventionconcerns a winding weight of this type intended to be fitted to awristwatch including a transparent back cover, said weight beingarranged on the side of the back cover of the case and allowingpermanent observation of the whole of the movement.

Wristwatches having cases with transparent back covers to allowobservation of their movement are already known. However, when thesewatches include a movement with automatic winding mechanism, observationof the movement is always curtailed by the presence of the oscillatingwinding weight which, even when pierced, as is the case in so-called<<skeleton>> watches, prevents comfortable observation of the movement.

SUMMARY OF THE INVENTION

The main object of the present invention is thus to overcome thedrawbacks of the aforementioned prior art, by providing an oscillatingwinding weight allowing observation of the movement to which it isfitted without any visible obstacle.

The invention thus concerns an oscillating winding weight for atimepiece including a heavy portion fixed to a connecting elementconnecting said heavy portion to an arbour fixed to a movement, saidweight being intended to be rotatably mounted on said arbour,characterised in that said connecting element is made of a transparentor translucent material.

As a result of this new winding weight structure, it is possible to makethe whole of the movement of the timepiece to which it is fittedpermanently visible, which gives the timepiece an improved aestheticappearance.

According to a preferred embodiment of the invention, the connectingelement is formed of a full sapphire disc.

It will be noted in particular in this respect that the use of sapphirein a winding weight as a connecting element between the heavy portionand the movement goes against the preconceived ideas of those skilled inthe art who, when having to design winding weights, always tend to usematerials having a high strength, i.e. a good capacity to absorb theshocks to which the weight is subjected during its rotation.

According to another aspect, the invention also concerns a timepieceincluding a case formed of a middle part closed by a crystal and an atleast partially transparent back cover and in which clockwork movementwith an automatic winding mechanism is housed, characterised in thatsaid movement is fitted with an oscillating winding weight as definedhereinbefore.

BRIEF DESCRIPTION OF THE DRAWINGS

Other features and advantages of the present invention will appear inthe following description of a preferred embodiment, given by way of nonlimiting example with reference to the annexed drawings, in which:

FIG. 1 is a plan view of a first embodiment of an oscillating windingweight according to the invention;

FIG. 2 is a cross-section along the line II—II of FIG. 1;

FIG. 3 is a plan view of a second embodiment of an oscillating windingweight according to the invention;

FIG. 4 is a cross-section, similar to that shown in FIG. 2, of a thirdembodiment according to the invention;

FIG. 5 is a plan view of a fourth embodiment of an oscillating windingweight according to the invention;

FIG. 6 is a partial cross-section along the line VI—VI of FIG. 5;

FIG. 7 is a cross-section of a fifth embodiment according to theinvention; and

FIG. 8 is a sectional view of a timepiece embodying the weight of FIG.1.

DETAILED DESCRIPTION OF THE INVENTION

FIGS. 1 and 2 show a first embodiment of an oscillating winding weightaccording to the invention, designated by the general reference 1. Asshown in FIG. 8, this weight 108 is intended to be fitted in aconventional manner to the automatic or self winding movement 110 of atimepiece 101 including a case formed of a middle part 102 closed by acrystal 106 and an at least partially transparent back cover 104 to makethe movement 110 visible from the back cover 104.

Winding weight 1 includes a heavy portion 2 fixed to a connectingclement 4 connecting the heavy portion to an arbour 16 fixed with aclockwork movement, weight 1 being intended to be rotatably mounted onsaid arbour. For this purpose, the connecting element includes at itscentre an opening 6 into which a ring 8, forming the hub of weight 1 isdriven.

According to the invention, connecting element 4 is formed of a fulldisc made of a transparent material such as sapphire which allows themovement to be observed through weight 1. It goes without saying thatany other transparent or translucent, synthetic or natural material canbe used. In all cases, the material will have at least to allow light topass through to be able to distinguish the shapes of the elementssituated behind it.

Heavy portion 2 includes a ring 10 which includes on an arc of a circleof approximately 180° an unbalance 12 which is formed by anoverthickness of said ring 10. In the example illustrated, ring 10 andunbalance 12 are made in a single part. Preferably, heavy portion 2 ismade of a high density metal, for example, a tungsten alloy. However, itgoes without saying that according to a variant, unbalance 12 can besecured to ring 10 by any conventional securing means such as screwing,bonding, crimping, soldering or suchlike. In this case, ring 10 can bemade of a material which is easy to machine, such as steel, andunbalance 12 of a tungsten alloy. In the example shown, ring 10 includesa rabbet 14 in which disc 4 is engaged and bonded. However, it goeswithout saying that according to a variant, this disc 4 can be fixed inrabbet 14 by any other conventional securing means such as screwing,riveting or suchlike.

FIG. 3 shows a second embodiment of an oscillating winding weightaccording to the invention. In this Figure and the following Figures,the elements which are identical to those described in connection withFIGS. 1 and 2 have been designated by the same numerical references. Itwill also be noted that, for the purposes of clarity, ring 8 forming thehub of weight 1 has been omitted from FIG. 3.

Unlike the embodiment shown in FIGS. 1 and 2, connecting element 4 ofthis embodiment is formed of a partially hollowed disc which is alsomade of sapphire. More precisely, connecting element 4 includes acentral portion 16 provided with opening 6 and a peripheral ring 18concentric with opening 6, central portion 16 being connected toperipheral ring 18 by three arms 20. The recesses of disc 4 willadvantageously be made using diamond wheels or using a laser beam.

FIG. 4 shows a third embodiment of an oscillating winding weight 1according to the invention wherein connecting element 4 is formed of acircular optical magnifying lens. It goes without saying that accordingto alternative embodiments, any other type of optical lens can beenvisaged. One could in particular provide Fresnel lenses which have thepeculiarity of being flatter than a conventional lens for a givenmagnification. One could also envisage using lenses producingkaleidoscopic effects for connecting elements 4.

FIGS. 5 and 6 show a fourth embodiment of an oscillating winding weightaccording to the invention wherein connecting element 4 is formed of atransparent plate in the shape of an angular sector extending overapproximately 180° and wherein heavy portion 2 is formed by a ringportion extending to the periphery of plate 4 over an arc of a circle ofapproximately 180°. Plate 4 is made of sapphire and further includes anoptical magnifying glass 22 which extends radially from ring 8 to thering of heavy portion 2.

FIG. 7 shows a fifth embodiment of an oscillating winding weight 1according to the invention wherein connecting element 4 is formed of atransparent plate in the shape of an angular sector extending overapproximately 180° and including at its periphery an edge 24 bent in aslant. In this embodiment heavy portion 2 is also formed by a ringportion extending over an arc of a circle of approximately 180° andfixed by means of screws 26 onto the inner face 28 of edge 24. It willbe noted that, as a result of bent edge 24, this embodiment ofoscillating weight 1 allows it be better fitted to the outer shape ofthe movement to which it is intended to be fitted, it being understoodthat edge 24 is bent in the direction of the movement.

What is claimed is:
 1. Oscillating winding weight for a timepieceincluding a heavy portion secured to a connecting element connectingsaid heavy portion to an arbour fixed to a movement of the timepiece,said weight being intended to be rotatably mounted on said arbour,characterised in that said connecting element is made of a transparentor translucent material.
 2. Winding weight according to claim 1,characterised in that said connecting element is formed of a full disc.3. Winding weight according to claim 2, characterised in that saidconnecting element is made of sapphire.
 4. Winding weight according toclaim 3, characterised in that said heavy portion is formed of a ringportion extending over an arc of a circle of approximately 180°. 5.Winding weight according to claim 3, characterised in that said heavyportion is formed of a circular ring including, over an arc of a circleof approximately 180°, an unbalance.
 6. Winding weight according toclaims 3, characterised in that said heavy portion is secured to saidconnecting element by bonding.
 7. Winding weight according to claim 1,characterised in that said connecting element is formed of an at leastpartially hollowed disc.
 8. Winding weight according to claim 1,characterised in that said connecting element is formed of at least twoconnecting arms.
 9. Winding weight according to claim 1, characterisedin that said connecting element includes an optical lens.
 10. Timepieceincluding a case formed of a middle part closed by a crystal, an atleast partially transparent back cover, and a self winding clockworkmovement housed in said case, characterised in that said movement isfitted with an oscillating winding weight including a heavy portionsecured to a connecting element connecting said heavy portion to anarbour fixed to said movement, said weight being intended to berotatably mounted on said arbour, said collecting element being made ofa transparent or translucent material.